Advanced Cardiac Life Support: The use of sophisticated methods and equipment to treat cardiopulmonary arrest. Advanced Cardiac Life Support (ACLS) includes the use of specialized equipment to maintain the airway, early defibrillation and pharmacological therapy.Heart Arrest: Cessation of heart beat or MYOCARDIAL CONTRACTION. If it is treated within a few minutes, heart arrest can be reversed in most cases to normal cardiac rhythm and effective circulation.Cardiopulmonary Resuscitation: The artificial substitution of heart and lung action as indicated for HEART ARREST resulting from electric shock, DROWNING, respiratory arrest, or other causes. The two major components of cardiopulmonary resuscitation are artificial ventilation (RESPIRATION, ARTIFICIAL) and closed-chest CARDIAC MASSAGE.Life Support Care: Care provided patients requiring extraordinary therapeutic measures in order to sustain and prolong life.Heart Massage: Rhythmic compression of the heart by pressure applied manually over the sternum (closed heart massage) or directly to the heart through an opening in the chest wall (open heart massage). It is done to reinstate and maintain circulation. (Dorland, 28th ed)Emergency Medical Services: Services specifically designed, staffed, and equipped for the emergency care of patients.Resuscitation: The restoration to life or consciousness of one apparently dead. (Dorland, 27th ed)Life Support Systems: Systems that provide all or most of the items necessary for maintaining life and health. Provisions are made for the supplying of oxygen, food, water, temperature and pressure control, disposition of carbon dioxide and body waste. The milieu may be a spacecraft, a submarine, or the surface of the moon. In medical care, usually under hospital conditions, LIFE SUPPORT CARE is available. (From Webster's New Collegiate Dictionary)Ventricular Fibrillation: A potentially lethal cardiac arrhythmia that is characterized by uncoordinated extremely rapid firing of electrical impulses (400-600/min) in HEART VENTRICLES. Such asynchronous ventricular quivering or fibrillation prevents any effective cardiac output and results in unconsciousness (SYNCOPE). It is one of the major electrocardiographic patterns seen with CARDIAC ARREST.